The history of the establishmment of Kollam Era in 825 AD is shrouded in mystery.
There are conflicting claims regarding the origin of Kollam Era.
King Udaya Marthanda Varma, Nestorian fathers, Sankaracharya, and Cheraman Perumal
are cited as having a role in the establishment of Kollam Era, which was supposedly established when the town of Kollam (Quilon) was founded.

The Malayalam Calendar is a solar calendar (i.e., dates are synchronized to Sunís declination).
However, lunar names of days (Nal) are provided in the calendar.
Nal is one of the five items (Panchangam) listed for each day in the Malayalam Calendar.
Nal corresponds to a star or asterism (called Nakshathram in Malayalam) transited by the Moon during that "day"
(day is in quotations since it is not a 24-hour period and its length varies). There are 27 stars in this system;
each star corresponds to a Nal. The Moon keeps transiting these 27 stars during its period of rotation around the earth.

Two different new years, based on the Malayalam Calander, are celebrated in Kerala.
The first day of the month of Chingam (Leo in latin, ~ August 17) is the official start of the New Year in the Malayalam Calendar.
The first day of Medam (Aries, ~ April 14) is also celebrated as the New Year and it corresponds to the Vishu festival.
I have seen "astrological" references to Medam 1 as the date when sun crosses the equator.
This is nonsense since Medam 1 is three weeks after the vernal equinox. Medam 1 is when sun is at its peak in
centreal Travancore, slightly north of Quilon.

First day of Kanni (Virgo), is regarded as the official start of the new year in northern Kerala.

Interesting Calendar Proposals:

Here are two interesting attempts to reform the universal Gregorian calendar:

Symmetry-454:

The
Symmetry454
calendar is a simple perpetual solar calendar that conserves the traditional 7-day week,
has symmetrical equal quarters comprised of 4+5+4 weeks, and starts every month on Monday.
Most months have just 28 days. Four months, including February, have 35 days.

The World Calendar:

The World Calendar
is similar to the Gregorian calendar. It has symmetrical quarters. Additional day for leap year is in June rather than in February. Addition of a so-called Worldsday
at the very end of the year disrupts the familiar 7-day week.